i would say to open a thread at VM forums here
http://community.virginmedia.com/t5/...nd/bd-p/100_mb
When had many T3 & T4 time outs in sort time (not as many as you)...an engineer came and add instead of splitter a distribution unit
Still had for some time even with the unit some issues but not as much
Now i have take it out and the usal splitter is back because i did not had T3 time outs for a while...it seems is gone by it self ...so in my case i think was from the network because at that time they was doing area work to that period according to double speed checker...but the main reason i am posting is to post at VM forums where they may send an engineer out